An analytic homogenization model in traction and bending for orthotropic composite plates with the type of double corrugated cardboard

In this paper, an analytic homogenization model in traction and flexion for the double corrugated cardboard plates is presented. The proposed analytical homogenization model allows modelling the 3D double corrugated cardboard with a 2D homogenized plate. This model is essentially based on the theory of stratification and then improved by using the theory of sandwich. This model was validated by comparing the results of Abaqus-3D and H-2D model using "user's subroutine" "UGENS". The homogenization model can be used not only for corrugated cardboard plates, but also for naval and aeronautic composite structure

PERSPECTIVES ON PERCEPTIONS AND PRACTICE THROUGH LEARNING CULTURES OF ENGLISH-SPEAKING COUNTRIES OF HIGH-QUALITY ENGLISH STUDIES PROGRAM STUDENTS, SCHOOL OF FOREIGN LANGUAGES, CAN THO UNIVERSITY, VIETNAM

The overall goal of the project is to understand the awareness or perceptions and practice of students of the High-quality English Studies program, School of Foreign Languages (SFL), Can Tho University (CTU), Vietnam when studying cultures of English-speaking countries (CESCs) to improve intercultural competence. The research on the perspectives or opinions of 200 High-quality English Studies students, 12 of them joining the semi-structured interview, about their awareness and practice through learning CESCs. The analysis would help the researcher understand the difficulties of students when studying cultural modules from English-speaking countries at SFL, CTU. The research results would suggest solutions to overcome the difficulties that students encounter, and at the same time provide factors that contribute to improving the intercultural competence of language students. Also, through the research results, despite many obstacles in the process of absorbing culture from cultural modules, students still retain their interest and love for the course-CESCs. However, it can be seen that the difficulty that many students often encounter is still cultural differences, thereby raising awareness of the need to learn cultures for students. Next is to design teaching materials to become more attractive and attractive, proactively find opportunities to communicate with foreigners.  Article visualizations

Un modèle analytique d'homogénéisation 3D complet pour les plaques composites orthotropes de type carton ondulé

La modélisation des plaques composites en carton ondulé est fastidieuse et couteuse en temps CPU. On propose un modèle d'homogénéisation analytique 3D complet en 2 étapes. A la première étape, on détermine les rigidités globales d'une plaque homogène équivalente. A la deuxième étape, on retransforme la plaque homogénéisée en un solide orthotrope composé de plusieurs couches et on identifie les paramètres des matériaux à partir de ces rigidités globales pour prendre en compte le comportement élasto-plastique suivant l'épaisseur. Le modèle est validé à l'aide du logiciel Abaqus

CSA: Thực hành nông nghiệp thông minh với khí hậu ở Việt Nam

During the last five years, Vietnam has been one of the countries most affected by climate change. Severe typhoons, flooding, cold spells, salinity intrusion, and drought have affected agriculture production across the country, from upland to lowland regions. Fortunately for Vietnam, continuous work in developing climate-smart agriculture has been occurring in research organizations and among innovative farmers and entrepreneurs. Application of various CSA practices and technologies to adapt to the impact of climate change in agriculture production have been expanding. However, there is a need to accelerate the scaling process of these practices and technologies in order to ensure growth of agriculture production and food security, increase income of farmers, make farming climate resilient, and contribute to global climate change mitigation. This book aims to provide basic information to researchers, managers, and technicians and extentionists at different levels on what CSA practices and technologies can be up scaled in different locations in Vietnam

Mapping for engagement: setting up a community based participatory research project to reach underserved communities at risk for Hepatitis C in Ho Chi Minh City, Vietnam

Background: Approximately 1. 07 million people in Vietnam are infected with hepatitis C virus (HCV). To address this epidemic, the South East Asian Research Collaborative in Hepatitis (SEARCH) launched a 600-patient cohort study and two clinical trials, both investigating shortened treatment strategies for chronic HCV infection with direct-acting antiviral drugs. We conducted ethnographic research with a subset of trial participants and found that the majority were aware of HCV infection and its implications and were motivated to seek treatment. However, people who inject drugs (PWID), and other groups at risk for HCV were under-represented, although injecting drug use is associated with high rates of HCV. Material and Methods: We designed a community-based participatory research (CBPR) study to engage in dialogues surrounding HCV and other community-prioritized health issues with underserved groups at risk for HCV in Ho Chi Minh City. The project consists of three phases: situation analysis, CBPR implementation, and dissemination. In this paper, we describe the results of the first phase (i.e., the situation analysis) in which we conducted desk research and organized stakeholder mapping meetings with representatives from local non-government and community-based organizations where we used participatory research methods to identify and analyze key stakeholders working with underserved populations. Results: Twenty six institutions or groups working with the key underserved populations were identified. Insights about the challenges and dynamics of underserved communities were also gathered. Two working groups made up of representatives from the NGO and CBO level were formed. Discussion: Using the information provided by local key stakeholders to shape the project has helped us to build solid relationships, give the groups a sense of ownership from the early stages, and made the project more context specific. These steps are not only important preliminary steps for participatory studies but also for other research that takes place within the communities

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Numerical modeling of the dynamic behavior of complex packaging structures by homogenization methods.

Les palettes sont très largement utilisées pour le transport, le stockage et la manutention de marchandises. Une palette chargée de bouteilles d'eau (emballage tertiaire) est constituée : d'une palette en bois, des packs (emballages secondaires) contenant un ensemble de 6 bouteilles d'eau (emballages primaires) enveloppés par un film plastique, des intercalaires en carton ondulé, et d'une housse plastique rétractable ou étirable pour le maintien et la protection de la marchandise palettisée. L'objectif général de cette thèse est de modéliser et de simuler le comportement statique et dynamique d'une palette durant le transport routier à l'aide du logiciel Abaqus. La simulation détaillée des bouteilles, des packs et des intercalaires constituants la palette est très fastidieuse et complexe à mettre en œuvre. Nous proposons de réaliser l'homogénéisation sur les packs et les intercalaires pour diminuer largement le temps de préparation des géométries et des maillages, ainsi que le temps CPU. Un modèle d'homogénéisation de l'intercalaire en carton ondulé est proposé. Il consiste à calculer les rigidités globales pour une plaque homogène équivalente. Ce modèle d'homogénéisation analytique permet de calculer rapidement et correctement ces rigidités globales et leurs couplages. Le comportement suivant l'épaisseur de l'intercalaire a beaucoup d'influence sur le glissement des packs. Nous avons donc développé un modèle solide en trois couches pour prendre compte le comportement élasto-plastique suivant l'épaisseur. Le pack de 6 bouteilles d'eau a été homogénéisé en caractérisant son comportement global par des essais expérimentaux et des simulations par la méthode des éléments finis. Le remplacement des packs par des solides homogènes de forme simplifiée permet de diminuer largement le nombre d'éléments et d'éviter le traitement du contact bouteille-bouteille et bouteille-film. De nombreux essais expérimentaux et simulations numériques avec nos modèles d'homogénéisation ont été réalisés pour étudier le comportement statique et dynamique de palettes chargées de bouteilles d'eau. Les résultats obtenus par les essais expérimentaux et les simulations numériques sont comparés pour valider nos modèles d'homogénéisation.Pallet systems are widely used for the transport, storage, stacking and handling of goods. A pallet charged with bottles of water (tertiary packaging) is composed of: a wooden pallet, packs (secondary packaging) containing a set of 6 bottles of water (primary packaging) wrapped with a plastic film, the cardboard sheet insert, and a plastic film for the maintenance and protection of the palletized goods. The aim of this thesis is to model and to simulate the static and dynamic behaviors of a charged pallet during the transport using the Abaqus software. The detailed simulation of the bottles, the packs and the cardboard sheet inserts constituting the pallet is very tedious and complex. We propose to homogenize the packs and cardboard inserts to largely reduce the time for the preparation of geometries and meshes, as well as the CPU time. A homogenization model for the cardboard inserts is proposed. It consists in calculating the global stiffness of the equivalent homogeneous plate. This analytical homogenization model allows calculating these global rigidities and their couplings quickly and correctly. The behavior in the thickness direction of the cardboard has a great influence on the sliding of the packs. We have developed a three layers solid model to take into account the elasto-plastic behavior through the thickness. The pack of 6 bottles of water is homogenized by characterizing its global behavior by experimental measurements and simulations with the finite element method. Replacing the packs by a simplified homogeneous solid permit to greatly reduce the number of elements and avoid the contact treatment between bottle-bottle and bottle-film. Many experimental tests and numerical simulations using our homogenization models have been achieved to study the static and dynamic behaviors of pallets. The results obtained by experimental tests and numerical simulations are compared to validate our homogenization models

Modèle d'homogénéisation élasto-plastique pour des structures composites

International audienceCet article présente un modèle d'homogénéisation élasto-plastique pour des structures composites de type carton ondulé. Une plaque composée de deux couches planes et d'une couche ondulée est modélisée par une plaque orthotrope homogène. L'homogénéisation est réalisée par une intégration locale à travers l'épaisseur dans chaque couche, suivie d'une cummlation des contributions des trois couches. Un modèle élasto-plastique en contraintes planes est adopté pour modéliser le comportement des papiers cartons. Notre H-modèle est implémenté dans le code de calcul Abaqus à l'aide du sous-programme utilisateur Ugens. Les résultats obtenus par le H-modèle sont comparés à ceux obtenus par les simulations 3D du carton ondulé avec des éléments de coque. La comparaison montre l'efficacité et la précision de notre modèle d'homogénéisation élasto-plastique

Finite-element simulation with a homogenization model and experimental study of free drop tests of corrugated cardboard packaging

This paper presents experimental and numerical studies of drop tests of corrugated cardboard packaging containing different foam cushions. An efficient homogenization model for the corrugated cardboard has been developed. In our homogenized model, the corrugated cardboard is represented by a 2D plate. Instead of using a local constitutive law (relating the strains to the stresses) at each material point, the homogenization gives the global rigidities (relating the generalized strains to the resultant forces) for the equivalent homogeneous plate. This model was implemented into the FE software ABAQUS. The foam behaviour was experimentally determined and modelled using a crushable foam model of ABAQUS. The packages are tested in free fall from a given height on a rigid floor. The deceleration of the packed product was recorded using a triaxial accelerometer. The numerical results obtained using the FE simulation with the homogenized model agree well with the experimental results. We have also shown that the contribution of the corrugated cardboard box to the shock response could not be neglected in the design of cushioning package